Yeah, right, I just skimmed through your post this time, but it turned out my intuition was correct.
Ossuaries are weird ass thing to build! I visited one in Kudowa Zdroj, PL around 2-3years ago. It seems it was quite popular idea in this region of Europe.
Yeah. Creepy places. Google out some pictures of the Sedlec Ossuary in Kutna Hora though, that place is really unique. The decoration made of bones and skulls in there is so weirdly impressive...
Wow, fucking bone chandelier!
I remember the story from Kudowa-Zdrój Skull Chapel that it was meant to be a warning about tragedies of war since war casualties' bones were used there.
I can imagine only one more reason to build such thing - to warn your enemies :D Well, waiting for your post.
I don´t know the story behind the Kutna Hora Ossuary but now I got curious about it and will do my deep research to find out :D ;)